Even though there are only about 1,000 giant pandas left, there is hope for this beloved endangered species. A comprehensive genetic analysis of three wild giant panda populations shows that they still have enough genetic diversity to recover.
"From a strictly genetic perspective, the giant panda species and the three populations look promising...they have retained a large amount of diversity in each population," say Lu Zhi of Peking University in Beijing, China, Stephen O'Brien of the Laboratory of Genomic Diversity at the National Cancer Institute in Frederick, Maryland, and their co-authors in the December issue of Conservation Biology.
Despite its status as the "poster animal" of endangered species, little is known about the remaining populations of giant pandas in the wild. Historically, giant pandas lived in forests from China to northern Burma and Vietnam, but extensive deforestation has restricted the species to six alpine forest fragments in the rugged mountain ranges along the Tibetan plateau in western China. Assisted by conservation organizations, the Chinese government has recently stepped up efforts to protect the pandas: since 1993 the number of reserves has more than doubled (from 14 to 33), and they are monitored and patrolled more frequently.
However, biologists estimate that the remaining giant pandas are divided into about 25 populations with fewer than 20 individuals each. Because small, isolated populations are more likely to die out, this increases the risk that the species will become extinc. Lu, O'Brien and their colleagues analyzed the genetic variation in giant pandas primarily from populations in three mountain ranges: one that is separated from the others by a 75-mile-wide valley (Qinling) and two that are adjacent (Minshan and Qionglai).
The researchers found that the giant panda has moderate genetic diversity compared other carnivores. "The giant panda is comparable to the genetically healthy Serengeti lion population in its endemic diversity and far greater than the genetically compromised Asiatic lion from India's Gir forest or the Florida panther," says O'Brien.
While the giant panda's overall genetic diversity is encouraging, the researchers also found evidence that the Qinling panda population (which is across the valley from the other two) is genetically isolated. The results suggest that this isolation occurred within the last few thousand years, which coincides with the valley's settlement by Chinese people. Fortunately, despite the Qinling population's genetic isolation, there does not yet appear to be significant inbreeding.
Part of the key to saving giant pandas in the wild is restoring gene flow among populations. Lu, O'Brien and their colleagues recommend maintaining and reestablishing natural corridors between populations. This effort could be incorporated into the national forest conservation program (which includes a logging ban and ecological restoration) that the government launched in 1998.
This research was a collaboration between the Laboratory of Genomic Diversity at the NCI, Peking University, the Chinese Zoo Association and Wolong Nature Reserve. Lu and O'Brien's co-authors are: Wenshi Pan of Peking University in Beijing, China; Warren Johnson, Marilyn Menotti-Raymond, Noaya Yuhki and Janice Martenson, all of the Laboratory of Genomic Diversity at the National Cancer Institute in Frederick, Maryland; Susan Mainka of the Species Survival Commission, IUCN, in Gland, Switzerland; Huang Shi-Qiang of the Beijing Zoo in Beijing, China; and Zheng Zhihe and Guanghan Li of the Chengdu Research Base of Giant Panda Breeding in Sichuan, China.